Animals, including pets, are neither always sedentary nor always active, and pets, particularly dogs, should be exercised with walks or runs. Animal owners, too, should exercise. When both a pet dog is ready for a run and an owner is ready for physical activity, a bicycle ride with a dog in tow can make for a pleasant way for both owner and pet to get the exercise they need. However, riding a bicycle while holding a leash for a dog can be dangerous as dogs sometimes decide to run or walk in a direction other than the direction which the bike is heading. Such unwise decisions can pull the bicycle to the side and lead to accidents.
Further, it is can be difficult to predict for how long a pet will be able to walk or run. Taking a pet dog along on a bike ride can be troublesome should the dog become tired partway during the trip, and bicycles are often not configured to accommodate carrying a dog while also bicycling. One alternative is to go for a bicycle ride while simply carrying the animal in a trailer towed behind the bicycle, but this does not allow the dog to get the exercise that it needs.